@resolve-js/client

The @resolve-js/client library exposes an interface that you can use to communicate with the reSolve backend from JavaScript code. To initialize the client, call the library's getClient function:

import { getClient } from '@resolve-js/client'

const main = async resolveContext => {
  const client = getClient(resolveContext)
  ...

The getClient function takes a reSolve context as a parameter and returns an initialized client object. This object exposes the following functions:

Function Name	Description
command	Sends an aggregate command to the backend.
query	Queries a Read Model.
getStaticAssetUrl	Gets a static file's full URL.
getOriginPath	Returns an absolute URL within the application for the given relative path.
subscribe	Subscribes to View Model updates.
unsubscribe	Unsubscribes from View Model updates.

command

Sends an aggregate command to the backend.

Arguments

Argument Name	Description
cmd	An object that describes a command to send to the server.
options	An object that contains additional options for command execution.
callback	A callback to call on the server response or error.

The returned value is a promise that resolves to the command execution result.

Example

client.command(
  {
    aggregateName: 'Chat',
    type: 'postMessage',
    aggregateId: chatRoom,
    payload: {
      userName,
      message,
    },
  },
  {
    middleware: {
      error: [
        createRetryOnErrorMiddleware({
          attempts: 3,
          errors: [500],
          debug: true,
          period: 500,
        }),
      ],
    },
  },
  (err) => {
    if (err) {
      console.warn(`Error sending a command: ${err}`)
    }
  }
)

query

Queries a Read Model.

Arguments

Argument Name	Description
qr	An object that describes a query.
options	An object that contains additional query options.
callback	A callback to call on the server response or error.

The returned value is a promise that resolves to the query result.

Example

const { data } = await client.query({
  name: 'chat',
  aggregateIds: '*',
})

getStaticAssetUrl

Gets a static file's full URL.

Arguments

Argument Name	Description
assetPath	A string that specifies a relative URL path.

The returned value is a string that contains a full URL.

Example

var imagePath = client.getStaticAssetUrl('/account/image.jpg')

getOriginPath

Returns an absolute URL within the application for the given relative path.

Arguments

Argument Name	Description
path	A string that specifies a relative URL path.

The returned value is a string that contains a full URL.

Example

var commandsApiPath = client.getOriginPath('/api/commands')

subscribe

Subscribes to View Model updates.

Arguments

Argument Name	Description
url	A URL used to establish a WebSocket connection to a view model.
cursor	The data cursor used to traverse the events included into the query result set.
viewModelName	A string that specifies the name of a view model.
aggregateIds	A list of aggregate IDs for which to receive events.
handler	A function that handles incoming events.
subscribeCallback	A callback called on a successful subscription or an error.
resubscribeCallback	A callback called on a successful resubscription or an error.

The returned value is a promise that resolves to a subscription object.

Example

const chatViewModelUpdater = (event) => {
  const eventType = event != null && event.type != null ? event.type : null
  const eventHandler = chatViewModel.projection[eventType]

  if (typeof eventHandler === 'function') {
    chatViewModelState = eventHandler(chatViewModelState, event)
  }

  setImmediate(updateUI.bind(null, chatViewModelState))
}

await client.subscribe('chat', '*', chatViewModelUpdater)

unsubscribe

Unsubscribes from View Model updates.

Arguments

Argument Name	Description
subscription	An object returned by the subscribe function.

Example

await client.unsubscribe(subscription)